This study aimed to investigate the impacts of organic amendments on soil microbial response in different two contrasting agricultural soils in Zambia, sub-Saharan Africa. In sub-Saharan Africa, efforts have been made to increase its soil carbon (C) contents in agricultural systems, due to severe soil degradation related to soil C depletion. Thus, we conducted a field experiment using different organic amendments (e.g. cattle manure, maize residue, etc.) in sandy loam soils from Lusaka (clay-rich soils) and Kabwe (sand-rich soils) sites in Zambia. Changes in carbon dioxide (CO₂) emissions and bacterial abundance and community structures were monitored for 126 days. The organic amendments significantly increased CO₂ emissions, bacterial abundance and diversity, but only in the sand-rich soils in Kabwe site. These findings indicate that in Kabwe site, organic amendments altered microbial activity but might not have a major impact regarding the C sequestration in the soil. Contrastingly, abiotic factors such as soil mositure controlled the impacts of organic amendments on microbial activities in Lusaka site. Site, soil texture, and climate-specific strategies are needed to deal with the issues of soil C depletion in a semi-arid region.